blob: 1e0690f2c0a5256958544d26d7e276c1f12b99f9 [file] [log] [blame]
<?xml version="1.0" encoding="UTF-8"?>
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
KIND, either express or implied. See the License for the
specific language governing permissions and limitations
under the License.
<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="boolean">
<title>BOOLEAN Data Type</title>
<titlealts audience="PDF"><navtitle>BOOLEAN</navtitle></titlealts>
<data name="Category" value="Impala"/>
<data name="Category" value="Impala Data Types"/>
<data name="Category" value="SQL"/>
<data name="Category" value="Data Analysts"/>
<data name="Category" value="Developers"/>
<data name="Category" value="Schemas"/>
A data type used in <codeph>CREATE TABLE</codeph> and <codeph>ALTER TABLE</codeph> statements, representing a
single true/false choice.
<p conref="../shared/impala_common.xml#common/syntax_blurb"/>
In the column definition of a <codeph>CREATE TABLE</codeph> statement:
<codeblock><varname>column_name</varname> BOOLEAN</codeblock>
<b>Range:</b> <codeph>TRUE</codeph> or <codeph>FALSE</codeph>. Do not use quotation marks around the
<codeph>TRUE</codeph> and <codeph>FALSE</codeph> literal values. You can write the literal values in
uppercase, lowercase, or mixed case. The values queried from a table are always returned in lowercase,
<codeph>true</codeph> or <codeph>false</codeph>.
<b>Conversions:</b> Impala does not automatically convert any other type to <codeph>BOOLEAN</codeph>. All
conversions must use an explicit call to the <codeph>CAST()</codeph> function.
You can use <codeph>CAST()</codeph> to convert
<codeph>TINYINT</codeph>, <codeph>SMALLINT</codeph>,
<codeph>INT</codeph>, <codeph>BIGINT</codeph>, <codeph>FLOAT</codeph>, or <codeph>DOUBLE</codeph>
any integer or floating-point type to
<codeph>BOOLEAN</codeph>: a value of 0 represents <codeph>false</codeph>, and any non-zero value is converted
to <codeph>true</codeph>.
<codeblock>SELECT CAST(42 AS BOOLEAN) AS nonzero_int, CAST(99.44 AS BOOLEAN) AS nonzero_decimal,
CAST(000 AS BOOLEAN) AS zero_int, CAST(0.0 AS BOOLEAN) AS zero_decimal;
| nonzero_int | nonzero_decimal | zero_int | zero_decimal |
| true | true | false | false |
When you cast the opposite way, from <codeph>BOOLEAN</codeph> to a numeric type,
the result becomes either 1 or 0:
<codeblock>SELECT CAST(true AS INT) AS true_int, CAST(true AS DOUBLE) AS true_double,
CAST(false AS INT) AS false_int, CAST(false AS DOUBLE) AS false_double;
| true_int | true_double | false_int | false_double |
| 1 | 1 | 0 | 0 |
<p rev="1.4.0">
<!-- BOOLEAN-to-DECIMAL casting requested in IMPALA-991. As of Sept. 2014, designated "won't fix". -->
You can cast <codeph>DECIMAL</codeph> values to <codeph>BOOLEAN</codeph>, with the same treatment of zero and
non-zero values as the other numeric types. You cannot cast a <codeph>BOOLEAN</codeph> to a
You cannot cast a <codeph>STRING</codeph> value to <codeph>BOOLEAN</codeph>, although you can cast a
<codeph>BOOLEAN</codeph> value to <codeph>STRING</codeph>, returning <codeph>'1'</codeph> for
<codeph>true</codeph> values and <codeph>'0'</codeph> for <codeph>false</codeph> values.
Although you can cast a <codeph>TIMESTAMP</codeph> to a <codeph>BOOLEAN</codeph> or a
<codeph>BOOLEAN</codeph> to a <codeph>TIMESTAMP</codeph>, the results are unlikely to be useful. Any non-zero
<codeph>TIMESTAMP</codeph> (that is, any value other than <codeph>1970-01-01 00:00:00</codeph>) becomes
<codeph>TRUE</codeph> when converted to <codeph>BOOLEAN</codeph>, while <codeph>1970-01-01 00:00:00</codeph>
becomes <codeph>FALSE</codeph>. A value of <codeph>FALSE</codeph> becomes <codeph>1970-01-01
00:00:00</codeph> when converted to <codeph>BOOLEAN</codeph>, and <codeph>TRUE</codeph> becomes one second
past this epoch date, that is, <codeph>1970-01-01 00:00:01</codeph>.
<p conref="../shared/impala_common.xml#common/null_null_arguments"/>
<p conref="../shared/impala_common.xml#common/partitioning_blurb"/>
Do not use a <codeph>BOOLEAN</codeph> column as a partition key. Although you can create such a table,
subsequent operations produce errors:
<codeblock>[localhost:21000] &gt; create table truth_table (assertion string) partitioned by (truth boolean);
[localhost:21000] &gt; insert into truth_table values ('Pigs can fly',false);
ERROR: AnalysisException: INSERT into table with BOOLEAN partition column (truth) is not supported: partitioning.truth_table
<p conref="../shared/impala_common.xml#common/example_blurb"/>
<codeblock>SELECT 1 &lt; 2;
SELECT 2 = 5;
SELECT 100 &lt; NULL, 100 &gt; NULL;
CREATE TABLE assertions (claim STRING, really BOOLEAN);
("1 is less than 2", 1 &lt; 2),
("2 is the same as 5", 2 = 5),
("Grass is green", true),
("The moon is made of green cheese", false);
SELECT claim FROM assertions WHERE really = TRUE;
<p conref="../shared/impala_common.xml#common/hbase_ok"/>
<p conref="../shared/impala_common.xml#common/parquet_ok"/>
<p conref="../shared/impala_common.xml#common/text_bulky"/>
<!-- <p conref="../shared/impala_common.xml#common/compatibility_blurb"/> -->
<!-- <p conref="../shared/impala_common.xml#common/internals_blurb"/> -->
<!-- <p conref="../shared/impala_common.xml#common/added_in_20"/> -->
<p conref="../shared/impala_common.xml#common/column_stats_constant"/>
<!-- <p conref="../shared/impala_common.xml#common/restrictions_blurb"/> -->
<p conref="../shared/impala_common.xml#common/kudu_blurb"/>
<p conref="../shared/impala_common.xml#common/kudu_non_pk_data_type"/>
<!-- <p conref="../shared/impala_common.xml#common/related_info"/> -->
<b>Related information:</b> <xref href="impala_literals.xml#boolean_literals"/>,
<xref href="impala_operators.xml#operators"/>,
<xref href="impala_conditional_functions.xml#conditional_functions"/>